Air-supported spherical gyroscope



Jan. 24, 1961 F. K. MUELLER 2,958,954

AIR-SUPPORTED SPHERICAL GYROSCOPE Filed March 30, 1960 6 Sheets-Sheet 2 FRITZ K. MUELLER,

INVENTOR.

5.1mm, BY

ATTORNEYS Jan. 24, 1961 F. K. MUELLER 2,968,954

AIR-SUPPORTED SPHERICAL GYROSCOPE Filed March so, 1960 l e Sheets-Sheet s ll lli Fig. 3

FRITZ K. MUELLER,

INVENTOR.

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ATTORNEYS.

F. K. MUELLER AIR-SUPPORTED SPHERICAL GYROSCOPE Jan. 24, 1961 6 Sheets-Sheet 4 Filed March so, 1960 FRITZ K.MUE

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Jan. 24, 1961 F. K. MUELLER AIR-SUPPORTED SPHERICAL GYROSCOPE 6 Sheets-Sheet 5 Filed March 30, 1960 FRITZ K.MUELLER,

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Jan. 24, 1961 F. K. MUELLER ,9

' AIR-SUPPORTED SPHERICAL GYROSCOPE Filed March 30, 1960 6 Sheets-Sheet 6 FRITZ K.MUELLER, 9 INVENTOR.

S. I l

ATTORNEYS.

AIR-SUPPORTED @PI-fiEEJCAL GYRQSCOPE Fritz K. Mueller, Huntsville, Ala., assignor to the United States of America as represented by the Secretary of the Army Filed Mar. 30, 1960, Ser. No. 18,781

Claims. (Cl. 74-5.6)

(Granted under Title 35, US. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to a gyroscope having a rotary mass that is substantially spherical and frictionless.

Undesired precision of gyroscopic rotors has long been a difiicult problem in the gyroscopic art. In solving the problem, a rotor that is suspended in or from its driving means with little or no friction between it and the driving means is needed. A spherical rotary mass suspended within and driven by a spherical casing by means of air bearings may be utilized, but any unbalanced portions of the driving and supporting air film or any unbalanced flow of the air to or from the film would lead to inaccuracy of the gyroscope.

Accordingly, it is an object of this invention to provide a gyroscope comprising a driving element with a substantially spherical hollow space and a rotary, substantially spherical mass mounted within the hollow space and driven solely by means of an air film, said driving element having a plurality of groups of air inlet and outlet openings, the opposite flows of air in each group being balanced relative to each other and to those of other groups.

Another object of the invention is to provide a gyroscope having a hollow, gyroscopic rotor with a substantially spherical outer surface that is supported and driven by an air film, the force on the rotor by any semispherical part of the air film being equal to the force of a diametrically opposite semispherical part of the film.

A further object of the invention is to provide a gyroscope comprising a hollow, generally spherical casing that is mechanically driven by a motor, a spherical gyroscopic rotor supported and driven within the casing by an air film, and a bellows-like, thin-walled air chamber fixed to the outer surface of the spherical casing and having communication with the air film.

The foregoing and other objects will become more fully apparent from the following detailed description of exemplary structure embodying the invention and from the accompanying drawings, in which:

Figure 1 is a perspective view, partly in section, showing the gyroscope of the invention.

Figure 2 is a sectional view from a plane thru the central bore of the gyroscopic rotor.

Figure 3 is a semi-schematic view, mainly in section, showing an optical means for indicating a changed position of the gyroscopes motor-attached casing.

Figure 4 is a detailed, sectional view from the planes 44 of Figure 5, showing a gyroscopic rotor that has a continuously spherical outer surface.

Figure 5 is a bottom view of the detail of Figure 4.

Figure 6 is a schematic view that indicates a method of balancing the air inlet and outlet holes.

Figure 7 is a plan view of the lower half oi a sphereretaining casing that is provided with air inlets and outlets located in accordance with the scheme of Figure 6.

Figure 8 is a schematic view that indicates a second method of balancing the air inlet andoutlet holes.

Patented Jan. 2 2-, 196i ice Figure 9 is a plan view of the lower half of a sphereretaining casing, having air inlets and outlets that are placed in accordance with the scheme of Figure 8.

In Figures 1 and 2, the invention is shown as comprising: a motor 1, which is preferably an electric motor and has a rotor shaft 2; a hollow casing 3, fixed to drive shaft 2, and having generally spherical inner and. outer surfaces; a substantially spherical gyroscopic mass or rotor 4, having a bore 5, and supported on an air film between its outer surface and inner surface 6 of the hollow casing; and a bellows-like air chamber 7-8 that is in flow-communication with said air film via air-inlet holes 9.

Parts 7 and 8 are airtightly clamped to annular flanges 10 and it of casing 3, and these flanges are sealingly clamped together by means of welding or of bolts that extend thru openings 12 (Figure 7). Air chamber 7-8 may be of metal, and is thin-walled and annularly-ridged at 13 to allow for expansion and contraction due to changes in temperature. The upper and lower parts of this chamber are clamped to flanges it and 11 by means of bolts extending thru holes 14 in the flanges (Figure 7).

Compressed air or other gas is suppied from a source of pressurized gas thru apertured fitting 15, thru the bore in shaft 2, and thus to the upper space 16 of air chamber 7-8. Thru annularly arranged bores 18, the pressurized fluid flows into lower space 20; and from both spaces air moves into the air film thru the multiplicity of inlets 9, bored thru casing 3. At the center of each annular grouping of equidistantly-arrauged holes there is an airoutlet passage 22. These passages 22 lead to the space between chamber 78 and outer housing 24; and from this space the air is exhausted thru openings 26.

Outer housing 24 may be universally supported by means of gimbals of known design, or, alternatively, it may be fixed to the hull of a missile or other vehicle whose attitude is controlled.

The purpose of the bore 5 is to provide for gyroscopic stability in a single plane of the sphere. This bore is of a diameter that is calculated to insure the desired stability, and may vary, for example, from the relatively small hole of Figure 2 to the larger central space of Figure 4. In any event, the bore may be closed at its ends, as indicated in Figure 2, by plates or disks of glass, 27 and 28. As indicated in Figure 2, each of these disks may have an outer, spherical surface that conforms to the outer surface of sphere i Thus, a continuous air film on the ball is provided.

Disk 27 is of plain glass or plastic, or, alternatively as indicated in Figure 4, of metal. Disk 23, however, is made only of glass or transparent plastic, so that light rays may be transmitted to and from a mirror in one end of the bore. Plate 29 (Figure 4) also is of transparent material. 7

The optical apparatus shown in Figure 3 may be utilized for measuring the deviation of the missile or other gyroscope-supporting means from the freely suspended sphere 4, as it spins in its plane of rotation, which is normal to the axis of bore 5. This indicating apparatus comprises: a case 30; a source of light 32; a half-silvered mirror 34, which permits the passage of a portion of the light beam from 32; a mirror 3-5, mounted at one end of bore 5; and a photoelectric cell 33.

In the form of the gyroscope shown in Figures 1 and 3, the concave surface of mirror 36 is indented from the spherical surface of the ball, the diameter of the mirror is the same as that of the opposite recess 40, and each of these diameters is smaller than the diameter of openings 22 into the spherical interior of casing 3, Therefore, the reduction of the air-film torque on the ball at the mirror recess is balanced by an equal reduction of such torque at 40; and the ball may tilt a little relative to upper air outlet 22A and lower outlet 22B without unbalancing the forces on it from the air film.

In the form of the gyroscope rotor shownin Figure 4, the mirror, 36A, may have a diameterlarger than that "of outlet 22C, without disturbing the balance of the air-film torques. V

In Figure 6 one projection scheme for determining balanced locations of the air passages in casing 3 is shown. An inward projection of the desired sphere into a twelve-sided polyhedron (a regular dodecahedron) is made. Half of this dodecahedron is indicated in Figure 6, in the six equal pentagons, 42. At each corner of each pentagon there is schematically indicated, by a circle, an air inlet 9A (for supplying air to the film); and in the center of each pentagon there is located a circle schematically indicating an air outlet from the film, 225. The centers of circles 9A are at the corners of the dodecahedron and are located at the surface of the desired sphere. When the circles 9A and 228 are projected outward onto the desired spherical surface they thus indicate the locations on that surface of air inlets 9 and outlets 22. Conversely, openings 22 may be utilized as air inlets to the film, and openings 9 as outlets. In any event, each air outlet receives air from radiating directions and the lines of these directions form a plurality of equal angles where they intersect at the outlet; and the inlets that supply air toward any outlet are equidistantly located on a circle whose center is in the outlet. All outlets are equidistantly and symmetrically spaced around the sphere. This spacing is indicated in the plan view of the lower half of the spherical casing that is shown in Figure 7.

Since the force on the ball of any semispherical part of the air film is balanced by the force on the ball of the opposite semispherical part of the film, a large amount of pressure within the film itself is not necessary. Preferably, the area of each air outlet is larger than the total area of the surrounding inlets (for that outlet). Most of the load of the ball is supported in the portions of the air film that are immediately around the inlets. The number of the inlets therefore should be at a maximum, but in this balanced gyroscopic ball they must be symmetrically arranged around the ball. Such balanced arrangement with a maximum number of inlets may be obtained only by the scheme of Figure 6 or, alternatively, by the scheme shown in Figure 8. In the use of either of these projection schemes the centers of the resulting inlet and outlet holes around the ball are in the same location.

In the scheme for determining equidistant and balanced locations of the inlets and the outlets shown in Figures 8 and 9, a polyhedron of twenty equilateral triangles as is indicated. In the center of each triangle there is shown a circle schematically indicating a large air opening, surrounded by small openings that are schematically indicated at the points of the triangle. When these circles are projected to an enveloping sphere the resulting arrangement of the air openings, indicated in Figure 9, is obtained.

In both of these forms of the invention that are indicated in Figures 7 and 9, the total number of air inlets in the casing is an even number; and the total number of outlets also is an even number. Thus every hole of a given size is balanced by a diametrically opposite hole of the same size. Preferably, openings 9 are inlets and openings 22 are outlets.

In operation, a hose or pipe for the supply of air or other gas is fastened to fitting 15, and compressed gas flows into the gaseous film, and out of the gyroscope at 26. If conservation of the gas is desired, it may be piped from openings 26, back to a compressor in the airsupplying system.

When the contacting surfaces of the ball and its casing 3 are made of hard material--for example, of chromium plating-motor 1 may be started before beginning the supply of compressed air to said surfaces. In this event,

friction between the surfaces quickly would cause the ball to pick up speed and begin rotating at the speed of shaft 2. Then compressed air is supplied between the surfaces to float the ball in a nearly frictionless state. Due to the bore 5, centrifugal force causes the ball to rotate in a plane that is normal to the axis of the bore.

Alternatively and optionally, compressed air may be supplied to the clearance between the ball and its casing before starting the motor. Then, after an air film has formed around the spherical rotor, the motor is started, and it begins to drive shaft 2 and casing 3. The slight amount of friction in the nearly frictionless air film causes ball 4 to slowly begin rotating in the same direction as its housing 3. The ball increases speed; and by the time it is moving at the same speed as the casing centrifugal force has caused it to be rotating about the axis of its bore, which is also the axis of rotation of the casing. The reason why this planar orientation of the ball is achieved, without any means being provided outside the sphere to stabilize it, is that a substantial amount of rotor material has been removed from around the axis of the bore, with only a minimum of elimination of the air-film-supporting surface of the ball.

When the support that is fixed to casing 3 tilts from its desired attitude in space, the ball tends to continue to hold to its rotary plane; and the tilting motion is measured by the current from the photoelectric cell of Figure 3.

The invention comprehends various changes in structure from that herein illustrated, within the scope of the subjoined claims.

The following invention is claimed:

1. A gyroscope comprising: a substantially spherical gyroscopic rotor having a central bore and having an axis of gyroscopic rotation that coincides with the axis of said bore, said bore having sufficient diameter to insure that if said two axes are not aligned when the rotation of the rotor is begun centrifugal force causes them to move into coincidence during the starting phase of the gyroscopes operation; a casing around said rotor, having a substantially spherical inner surface that closely surrounds said rotor, with a clearance therebetween at all points, said casing having two sets of holes extending from its exterior to said clearance, one of said sets consisting of a plurality of annularly arranged groupings of gas-transmitting holes of relatively small diameter, and the other of said sets consisting of larger gas-transmitting holes that are located Within said annularly arranged groupings each of said sets having an even number of equidistantly-spaced holes, said casing and rotor being constructed and arranged to provide a gaseous film between them in which the force on the spherical rotor from any semispherical part of the film is balanced by the force on the rotor from the complementary semispherical part of the film; a motor drivably connected to said casing; means for supplying pressurized gas to one of said sets of holes, thereby forming a gaseous film in said clearance, while the other of said sets provides for exhaust of the gas from said clearance; whereby when said motor is started and drives said casing, said rotor is rotated, and increases its speed until it is rotating at substantially the speed of said casing, about the axis of rotation of said casing and said bore; and means for indicating a shift of said casing relative to said rotors axis of gyroscopic rotation.

2. A device as set forth in claim 1, in which the centers of said holes of relatively small diameter are arranged in a pattern that is symmetrical relative to the line of every possible acceleration upon said device, in which pattern straight lines linking said centers form a regular dodecahedron, subtended within the spherical inner surface or" said casing, each of said larger gas-transmitting holes being located at a point projected outwardly from the center of one of the pentagons of said regular doclecahedron.

3. A device as set forth in claim I, in which said rotor comprises a radiant-energy-reflecting disk mounted across one end of said bore, and which further comprises a housing adjacent said disk, said casing having an opening between said housing and disk and a plate of glass sealingly mounted across said opening; said device further comprising, within said housing, means for transmitting radiant energy via said opening to said disk and means for receiving radiant energy reflected from said radiantenergy-reflecting disk and for indicating any tilting movement of said casing relative to said bore.

4. A device as set forth in claim 3, which further comprises a second disk sealingly mounted over the end of said bore that is opposite from said first-named disk.

5. A gyroscope comprising: a motor; a generally spherical casing, having a substantially spherical inner surface, means drivably connecting said motor and easing; a generally spherical gyroscopic rotor within said inner surface, with a clearance therebetween; said casing having two sets of holes extending from its exterior to said clearance, one of said sets consisting of an even-numbered plurality of annularly arranged groupings of gas-transmitting passages of relatively small diameter, and the other of said sets consisting of larger gas-transmitting holes that are located within said annularly arranged groupings; a flexible, airtight envelope supported by and loosely surrounding a portion of said casing, said envelope inclosing one of said sets of holes, the other of said sets debouching at the outer surface of said casing, outside of said envelope; and means for supplying pressurized gas to the interior of said envelope, whereby gas is supplied to said clearance via said envelope and its inclosed set of holes, and whereby gas is exhausted from said clearance via the other set of holes and outside said envelope.

References Cited in the file of this patent UNITED STATES PATENTS 2,086,896 Carter July 13, 1937 2,613,538 Edelstein Oct. 14, 1952 2,729,106 Mathiesen Jan. 3, 1956 2,809,527 I Annen Oct. 15, 1957 

